Rivet and method of setting



Aug. 4.,1936'. L, C VHUQK l Re. 20,055

RIVE ANDY METHOD 0F SETTING- THE SAME .ofiginal Filed March 51, 1932v 2 sheets-sheet 1 l l Y.

I BY .i

Aug.

L. C. HUCK RIVET A ND METHOD SETTING THE SAME Rye.. 20,055

" Y original Filed'maroh 31, 1952 2 sheets-,sneer 2 'LEE-l E@ Reissued Aug.Y 4, 1936 N Re. 20,055

Y Louis C. Huck, Buchanan, Mich., asslgnor to Huxon Holding' Corporation, Detroit, Mich., a corporation of Michigan original No. 2,030,166, una Februar-y 11, 193s,

Serial No. 602,170, March 31, 1932. Application for reissue May 27, 1936, Serial No. 82.074

sz claim. (o1. zls-zs) 'Ihe invention relates to rivets and it has particular relation to a rivet construction, method of riveting and method of making the rivet.

Particularly the invention is related to my copending application for patent, vSerial No. 545,004, led June 17, 1931, now Patent No. 2,030,165, my

.copending application, Serial No. 578,314, led December 1, 193i, and my copending application, Serial No. 599,868, filed March 19, 1932, now abandoned.

In the above identified applications for patent, a rivet is disclosed which comprises a tubular female member adapted to project through openings ordinarily having slight clearance therefor, in a structure to be riveted, and a malel member extending through the female member which has a head at one end engaglngthat end of the female member first inserted in the structural openings. I'I'he rivet is particularly useful for inserting and riveting constructions from one side only, and the maximum diameter of that part ofthe female member passing into or through the openings, cannot be larger than the diameter of the latter. Preferably the end of the female member at the side of the structure from which the insertion is made or the working side, will have ahead initially formed although it may be formed'in the rivet setting operation, which engages -such working side of the structure.

After the rivet is thus inserted, the gripping end of the male member is pulled, and the reactionary force is applied to the adjacent end or head of the female member, during which operation, a bulb head is formed from the female member against the inner side ofthe structure.

For reinforcing that end of the female member adjacent the male member head, and increasing its bursting strength, a construction was 'disclosed in such applications for patent which provided for the formation of a bulb out of an annular wall portion of the female member, during the initial stages of the rivet setting operation, and this bulb head served to then prevent bursting or entering of the male member head into the adjacent end of the female vmember. For forming suchbulb, that end of theV female member had a portion of reduced wall thickness, between the main body of the female member and a collar thereon immediately adjacent the male member head. Following the formation of the bulb,Y continued pull on the male member caused, through the head on the latter, the collar and such bulb, bulbing of the main body portion of the female member to provide a bulb against the inner side of the structure. This brief description, of course, is illustrative only generally of the particular construction set forth in such applications for patent.

In general the objects of the present invention are similar to those set forth in such copending applications for patent. Y

More particularly, an object of the invention is to provide improved means for applying stress to that part of the female member to be bulbed. in such manner that the outer fibers `of such members are stressed more than the inner fibers.

Another object of the invention is to provide improved means for applyingA the stress to the female member in a direction longitudinally thereof, and slightly towards its axis.

Another object of the invention is to obtain the above mentioned stress applications in a rivet of the double bulblng type as described previously.

Another object of the invention is to provide a rivet of the general type indicated, which may readily be employed for supporting various articles on the structure riveted.

Another object of the invention is to obtain improvements which provide for the initial formation of a reinforcing bulb, to increase the bursting strength of an end of the female member, prior to forming the main bulb head.

Another object of the invention is to provide improvements in the methodof bulbing the rivet so that bulbing may be controlled for effecting a tightly riveted construction.

Another object of the invention is to provide a method of manufacturing a female member with an undercut groove therein, which will be simple and inexpensive.

Other objects of the invention will be apparent from the following description taken in conjunction with the drawings, and the claims hereinafter set forth.

For a better understanding of the invention reference may be had to the accompanying drawferent form of rivet assembly, and the manner in which the first head of the multiple head on the female rivet member is formed and the manner in which it then cooperates with theremalnder of the assembly.

Figures 8 and 9 similarly, fragmentarily illustrate a rivet assembly constructed according to another form of the invention, and the manner iniwhich the first head ofthe multiple head formation on the female member is obtained.

Figures 10 and 11 similarly illustrate a rivet assembly constructed according to another form of the invention, and the manner in which the first head of the multiple head is formed;

Figures 12 and 13 illustrate a rivet assembly, constructed according to still another form of the invention, and the manner in which the first of the heads on the female members is obtained;

Figure 14 is a cross-sectional view 'of a rivet which has been applied to secure structural elements together in which the female member may be employed for supporting various articles;

Figures l5, 16 and l'lillustrate steps which may be involved in manufacturing a female rivet member such as that illustrated in Figure 8.

According to one form of the invention, a female member Ill, as shown by Figure 1, is provided which is of tubular character, and is provided with a head II at one end. At the inner side of the head II the female member has an annular continuous Wall'body portion I2 substantially of uniform inner and outer diameter throughout its length and this body portion at its end remote with respect to the head I I, is integral with a smaller annular, and continuous tubular portion I3 having substantially the same inner diameter, but a smaller outer diameter. At the outer end of they portion I 3, an annular tubular collar or Yhead I4 is provided and the inner and outer diameters of this collar preferably substantially correspond to the inner and outer diameters of the body portion I2. The female member so described, is adapted to cooperate with a male shank member I5, extending through the female member and beyond. the head II on the latter, and which has a head I6 substantially equal in outer diameter to that of the collar I4, engaging the end face of the collar.V As initially assembled, it

substantially corresponding to the inner diameter of the body portion I2 so that a least a flt will be effected which will retain the parts assembled, although a press fit is preferable. Adjacent the head I6, the male member is provided with an annular groove II, although one or more circumferentially separated recesses may be employed in lieu of agroove, and such groove is located generally under the collar I4 as the purpose thereof is to allow the metal of the female member to flow inwardly thereinto during the rivet setting operation to positively lock the male and female members' together after the rivet is set. The face of the head lladjacent the groove I'I is undercut at a slight` angle as indicated at I8 and this angle.

for example, may be degrees with respect to the longitudinal axis of the male member. In this connection it is desired to point out that the end face of the collar I I in this construction, substantially defines a radial plane and it will follow that the end face IB of the head I6 therefore will initially engage the end face of the collar I4 only along the outer margin of the latter. It might be added, however, that the face I8 may be substantially radial and the end face of the collar beveled at substantially the aforementioned angle of 85, but oppositely to the bevel IB shown. This` arrangement would also cause initial engagement of the head and end face of the collar only along the outer margin of the latter.

In the application of a rivet of this character, structural elements such as indicated at 20 and 2i to be riveted together are rst provided with openings 22 substantially corresponding in diameter to the outer diameter of the body portion I2 of the female member although a slight clearance usually will be present and the outer diameter of thebody portion I2, collar Il, and the head I6 are such that these parts may be inserted through the openings 22, from one side of the structure, as for example, from that side outside of the element 2l, until the head I I abuts the structural element last mentioned. In setting the rivet it is to be understood that a suitable device or machine is employed for pulling the projecting end of the male member while applying an equal or greater force against the head II of the female member to hold it against the structural element 2|. A machine which may be used for this purpose is disclosed in the application for patent of Louis C. Huck and Ralph A. Miller, Serial No. 560,289, filed August 31, 1931, and comprises movable jaws for gripping the projecting end of the male member while applying the reactionary force when the male member is pulled by the jaws, against the head II of the female member. is desired to point out that the projecting end of the male member preferably may be threaded or provided with a plurality of shallow grooves 23 to facilitate obtaining greater gripping action between the jaws of the aforementioned machine and the male member and the jaws will preferably have complementary threads or ribs for cooperating With the threads or grooves on the male member.

In the rivet described the collar I4 has such axial length and resistance to axial deformation,

compared to the resistance of the portion I3 of v the female member to deformation, that in the initial pulling of the male member, the collar is axially deformed until it substantially fits the undercut I8 on the head I6 of the male member before the portion I3 of the female member is completely bulbed. Initial deformation of the collar before bulbing begins is illustrated ln Figure 2, and it will be noted that as the collar so takes the form of the undercut I8, its opposite face at the outer end of the portion I3 takes a bevel as indicated at 24 substantially parallel to the undercut. Nowas the male member continues to move, the weaker portion I3 of the female member begins to bulb outwardly and finally assumes substantially the shape shown in Figure 3 as indicated at 25. It should now be apparent that this bulbed head constitutes a reinforcement at the end of the portion I2 of the female memberv which will greatly facilitate bulbing the latter and prevent bursting or flaring of the female member end, when the greater force which isV necessary to bulb part I2 is applied. It may be pointed out here that the shoulder at either end of the reduced portion I3 initially substantially defines a radial plane and substantially sharp corners are providedat the end of such portion although it will be appreciated that .when the collar I4 is deformed as At this time it 3 shown in Figure 2, the shoulder thereon will be-v of the portion I2.ot the female member, along a radial plane 'area while the opposite side oi' collar I4, the latter being beveled, only along the outer margin of the beveled portion of said collar. Consequently, any further movement oi' the male member acting through the head IB and the collar I4 will cause a greater force to be exerted along the outermargin of the collar and the line of engagement of the collar with the head 2l. Acting through the head 2l, this greater stress will be transmitted to the outer bers of the end of the body portion I2. Owing to the angleof the shoulder on the collar I4 the force will be directed not only axially of the body portion but also toward the axis of the rivet. Either or both stress application features seemingly is instrumental in effecting location of the line of greatest diameter of the bulbing portion I2, nearer to the structure being riveted, than to the inner end of such portion I2, although such line may be substantially at the midway point. Preferably portion I2 bulbs in globular fashion,

section shows the portion substantially of uniform curvature. The head 28 thus formed is tight against the structure, and the manner of bulbing insures drawing of the plates together.

the fact that the male member preferably Ais provided with a neck 29 intermediate its ends, dened by a beveled surface 30 and a rounded surface 2i, the latter surface having substantially the same contour asthe outer surface of head II on the female member adjacent the opening therein. This neck on the male member is preferably, so located that following the rivet setting operation the bevel 3i Ais substantially ush with the outer surface of the female head Ii. Continued pull on the male member will so tension it that it will break at the neck 2l. since this is the weakest part of the male member, and as a resulto! the break as indicated at 32 in Figure 5, the broken end of the male member w'ill constitute substantially a continuation and ush portion of the female head II.

In such copending applications for patent exemplary metals and dimensions of the male and female members, were set forth and it should be understood that the metals and dimensions of the male and female members may be of the same character in this invention. As set forth in such copending applications, the dimensional relation of the parts in any size of rivet may vary appreciably without obtaining undesirable results, and this variation may depend to some extent for example upon the metals employed. In general, the inner diameter of the body I2 will be within the range of 68% to 83% of the outer diameter thereof, the outer diameter of the reduced part I3 within the range of 80% to 95% oi the outer diameter of body I2, and the length of fthe part I2 within the range of 30% to 75% oi' the outer diameter of the body I2. The length of collar I4 in the present case will be less than in such copending cases, as for Vexample Y@ of the length of part I3, so that the collar may, prior to complete bulbing of head 2,5, deform to t the undercut or bevel I8 on `the head. It will be understood that during or after bulblng, metal in the female member, adjacent the collar I4, ows into the groove I8, to lock the parts together after the rivet is set.

In the constructionrshown by Figures 6 and 7, the female member I0, at the end of the body I2 oppositethe head I I. has a portion 25 of reduced the bulbed head will engage the shoulder on the' as shown in Figure 4; .in which -an axial cross` At this time it is desired to call attention to wall thickness, but in contrast to the portion I3,

in Figure l, portion Il has its inner diameter enlarged and its outer diameter substantially the same as that of body I2. The length and wall thickness of portion 2l may be the same as that of portion I2 with respect to the outer diameter of body I2, but the collar I4 shown in Figure 6, preferably is longer than the collar in Figure 1. The portion Ii bulbs substantially as shown in Figure 7, and the body I2 will then bulb substantially as shown in Figure 4, to provide a head 23 as shown in Figure 5. 'Ihe metal in the collar I4, during the riveting operation, likewise will ow into the groove I1, to lock the parts together. In this construction the outer bers of the female member will be stressed to a greater extent than the inner bers. y

The rivet assembly shown by Figures 8 and 9 obtains a similar result to that of Figure 1, but in a different way. In this construction the female member is provided with a portion I3 in which the walls at the end thereof indicated at 4U and 4I are both undercut although it might be desirable to undercut only one wall. As the portion I3 bulbs. as shown by Figure 9, it is apparent that one or both of these undercut portions 40 and 4I will cause the application of greater forces to the outer bers of the body portion "I2 for substantially the same reasons pointed out previously as it will be apparent that such undercut portions along their outer margins will engage the bulb and hence the outer fibers of the body portion I2 will be stressed to a greater extent than the inner bers.

A similar result is obtained in the assembly shown by Figures l and 11. In this construction, the portion I2 of the female member has outer wall surfaces 42 and 42 slightly converging outwardly toward the center line and when thisl portion is bulbed as shown by Figure ll, it is apparent that the bulb formed as shownl at 45 will be of such character that the collar I4 acting through the bulb will still apply a greater for-:e to the outer bers in the body portion I2.

The construction shown by Figures 12 and 13 is similar to that shown by Figures andll with the exception that the portion I3 has an arcuate outer surface .indicated at 41 with the, thicker portion midway between the ends thereof. After the rst bulb is formed, as indicated at 48 in Figure 13, the collar I4 will stress the outer bers of the portion I2 to a greater extent than the inner bers.

All of the rivet assemblies described and shown in the previous description, relate to the formation of a rst bulbed reinforcing head, which is then instrumental in forming a second and stronger bulbed head. In each case this is effected by an arrangement which preferably stresses the outer bers rst, as it seems that bulbing of the second head is very satisfactorily obtained in this manner. Moreover, in at leastthe construction shown by Figure 1, the force of the male head I6 is transmitted through the first bulbed head to the portion I2 of the female member in an .axially inclined direction toward the axis of the rivet. It should be apparent that in any of the constructions the beveled face on the head II of the male member may be employed,

and also that one or both undercuts as shown in Figure 8 in the female member, might also be employed if found desirable. Moreover, it is entirely possible to use the collar I4 shown by Figure 2 which initially takes the form of a beveled head on the male members in any of the constructions as apparently any initially formed` bevel of this character in the female member or bevel formed during the initial movement of the male member would help to obtain the result of greater stressing of the outer fibers of the portion I2 of the female member and hence bulbing as described. In any of the rivets. the male and female members are locked mechanically in a positive manner against relative axial movement after the rivet is set. As more particularly described in my copending applications for patent, in setting the rivet, the female member may be enlarged to nil up any interstices between it and the openings inthe structural elements, and that similarly this may increase any press flt or effect a press iit between the male and female members so that a-flnal tight fit is obtainedbetween the parts.

'I'he construction shown by Figure 14 may be a modication of any of the constructions previously described and in this case the male member will be broken of! inwardly of the outer surface of the head Il on the female member. Either during the manufacture of the female member or afterwards, the remaining opening i in the head il indicated at 80 may be threaded.

The threaded opening may be utilized as a means for supporting articles on the rivets and as shown, a machine bolt 6l may be threaded into the head and against a hook B2 for example. so that various articles may be supported on the structure by means of the rivet. It is manifest that utilization of the rivet in'this manner would not substantially aiIect its utility for connecting structural elements together.

Figures 15, 16 and 17 are illustrative of a method of manufacturing the female member shown by Figure 8. As shown by Figure 15, the female member initially may be solid as indicated at il and then by means of rollers indicated at il in Figure I6, a groove B5 may be formed in the end portion of the female member defined at its ends by plane radial faces Si and 81. Normally, during such formation of a groove, portions of the member at opposite ends of the"I groove will be bulged outwardly as indicated at il.

Now, by applying other rollers indicated at il in Figure 17, such bulged out portions l. may again be brought into alignment with the outer surface of the member and during this formation the groovel 85 will be dened by end faces `having bevels indicated at lll. After the groove $5 is thus formed the member may be drilled to provide a tubular construction as shown by Figure 8.

It may also be stated that preferably the female member is composed of lmetal more ductile than the male member. Examples of various combinationsv of metal that may be used have already been disclosed in my previously identied ccpenling applications for patent.

From the above description it is apparent that a rivet has been provided particularly in' which a plurality of heads are formed on the female member by pulling amale member therethrough and applying the reactionary force of the pull to the head at the other end of the female member. The important function of the first bulb head formed at the inner end of the female member is to provide a flange to increase lthe bursting ystrength of this tubular end of the female member. Moreover it will be seen that constructions I have been provided for the application of presvto a greater extent than on the inner fibers, as 'it has been found that either or both features locates the line of greatest diameter of bulbing nearer to the structure than to the inner end of the bulbing portion I2. Also it is apparent that a rivet construction has been provided in which the male member breaks substantially flush with the head on the female member and with substantially the same contour so that finally the head onthe female member seemingly has the appearance of the ordinary rivet head. In this construction, it is apparent that whether or not the male member breaks at this point may be considered a determining factor as to whether or not the head on the inner end of the female vmember is formed in a proper manner. Moreover, it is apparent that by having the male member break inwardly of the outer surface of the female member head the rivet may be employed for supporting'various articles as described by threading for example the open end of the rivet head. Additionally. rivet constructions of the single bulbed head have been illustrated and described, in which particularly improved means are utilized yfor applying a greater stress to the outer fibers during the formation of the bulbed head from the portion I2 of the female member, for` direct'- ing the stress at an angle to the rivet axis and for locking the male and female members together against relative axial movement. In general the invention constitutes a highly efllcient rivet construction, which makes it possible to rivet a structure in an extremely strong, rapid and eillclent manner from one side only of the structure. -It will be appreciated that formation of the head on the inner end of the female member is a paramount problem, if the rivet assembly is to be inserted only from one` side of the structure, and if the rivet is to have the necessary strength and is to be tight. The invention achieves this result in a highly satisfactory manner as it has been determined that the rivet is extremely strong .and that in fact parts of the structure riveted will fail prior to failure of the rivet.

Although various forms of the invention have been described and illustrated in detail, it should be apparent to those skilled in the art that various modiilcationsmay be made without departing from the scope of the appended claims.

I claim:

1. The method of riveting which comprises providing a tubular member, forming a reinforcing head on one end of the member and then applying axial forces through such head and in such manner as to stress the outer fibers of another part of the member to a greater extent than the inner fibers, and to bulb out said part.

2. The method of riveting which comprises providing a tubular member, forming a reinforcing head on one end of the member, and then applying forces to the end of such member through such head in a direction longitudinally of the other part of the member to bulb the latter, and

in such manner that the forces stress the outer fibers of such latter part more than the inner fibers at least adjacent the reinforcing head.

4. 'I'he method of riveting which comprises providing a tubular member, bulbing la portion of the member to form a reinforcing head, and their applying axial forces through such head to another part oi the member to bulb the latter, and in such, manner that the forces are directed longitudinally and slightly toward the axis of the member.

5. A rivet comprising a tubular member in which portions thereof have dlerent resistances tofoutward expansion, and means includingv a member extending through the first member for stressing the outer ilbers of the latter, to an extent greater than the inner fibers are stressed.

6. A rivet assembly comprising a tubular member having an end portion of reduced outer diameter, and a collar at the outer end of the latter. anda shank extending through'the tubular member and having a head engaging the end face of the collar, said parts being so constructed and related that when the shank is pulled through the member in a direction tov urge the head against the collar, the reduced portion of the member and a portion thereof adjacent thereto bulb outwardly in sequential order, and during bulbing of the latter portion, its outward bers are stressed more than its inner fibers.

'1. A rivet comprising 'a continuously annular tubular member having a portion adjacent one end of reduced wall thickness, the shoulder between such portion of reduced wall thickness and respect to the axis of the member.

8. A rivet comprising a continuously annular wall thickness, and an enlarged collar at the free end of the latter, one of the shoulders at the ends of such reduced portion, being tapered with respect to the rivet axis.

9. A rivet comprising a tubular member having a collar adjacent one end thereof which is of increased radial .wall thickness with respect said collar being less resistant to bending axially over such portion of the member of reduced wall thickness, than the latter portion is to outward bulbing, so that compressive forces applied to opposed ends of the member, first will bend the collar over, and then bulb the portion of the member adjacent thereto.

10. A rivet comprising a tubular member having axially distinct portions adapted to bulb sequentially in the rivet setting operation, one of said portions being denne'd by an axial portion having irregular wall thickness.

11. A rivet comprising a tubular member having axially distinct portions adapted rto bulb sequentially in the rivet setting operation, one of said portions being deilned by an axial portion having' irregular -wall thickness, said last portion having greatest wall thickness intermediate its ends. 4

' l2. A rivet comprising a tubular member having axially distinct portions adapted to bulb sequentially in the rivet setting operation, one of said portions being defined by an axial portion having irregular wall thickness, said last portion having greatest wall thickness intermediate its ends, and being progressively less thick toward the ends.

13. A rivet comprising a tubular member having annular, axially distinct portions for bulbing in sequential order upon application oi compressive forces Yto the ends of the member, and means for effecting greater stress application to the outer bers of the last bulbing portion, upon application of such compressive forces.

14. A rivet comprising a4 tubular member havthe remainder of the member being tapered with tubular member having a portion of reduced a to a portion of the member adjacent thereto, i

ing annular, axially distinct portions for bulbing in sequential order upon application of compressive forces to the ends of the member, and means for eecting greater stress application to the outer bers of the last bulbing portion, upon 5 application of such compressive forces, said means comprising a tapered shoulder at one end of the portion to be bulbed first.

15. 'A rivet comprising a tubular member having annular, axially distinct portions for bulbing in sequential order upon application of compressive forces to the ends of the member, and means for eil'ecting greater stress application to the outer ilbers of the last bulbing portion, upon application of such compressive forces, said means comprising an enlarged sector of the portion to be bulbed first.

16.V A rivet comprising a female member of tubular character having a head at one end provided with a threaded aperture. a male member having a head engaging theopposite end of 'the female member and a shank portion extending therethrough and through the threaded aperture, the shank portion of such male member terminating inwardly of the exposed end of the threaded opening in the head of the female member, whereby fastening devices may be secured in said threaded aperture.

1'1.V The method of riveting which comprises providinga tubular member, applying forces to opposite ends of the member to bulb out a part of the member, and subsequently applying similar i'orces to bulb out a second part of the member. A

18. The method oi riveting 'which comprises providing a tubular member, and forming a pair of adjacent bulbed out head portions in one part of the member.

19. The method of riveting which comprises providing a tubular member with a continuously o annular wall, and forming a pair of bulbed out head portions in adjacent parts of the member.

20. The method of riveting which comprises providing a tubular member with a head at one end and a tubular body portion, forming a head on the other end of the body portion to increase the bursting strength of such end, and then bulbing out a portion of the body intermediate its ends. y

. 2l. A rivet comprising a tubular female member having a part adapted to project through openings in a structure -to be riveted, a part to be disposed at one side of the structure and to be bulbed into a head, and a part oi' reduced radial dimensions 55 at the end of the second part, wherein the inner diameter of said first and second parts may vary approximately from 68 to 83 per cent of the outer diameter thereof, and the radial dimensions of the third part may vary approximately from 80 60 to 95 per cent oi' the radialdimensions of such nrst and second parts.

22. A rivet comprising a tubular member having a plurality of abutting bulbed portions of different axial dimensions.

23. Av rivet comprising a tubular member having a pluralityof bulbed portions at one end, said bulbed portions being adjacent and reinforcing one to the other in head formation. v

l 24. A rivet comprising a tubular member having 70 a plurality of abutting bulbed`portionsv of different radial dimensions.

25. A rivet comprising a tubular member adapted to extend through openings in a structure and to project beyond one side of the structure, and

expansible means inherent in the member at its projecting end and adapted to increase the bursting strength of the latter when axially compressive forces are applied to opposite ends of the ing head, to bulb out a second portion thereof.

28. A rivet assembly comprising a tubular member having an end portion of reduced outer diameter, and a collar at the outer end of'the latter, and a shank extending through the tubular member and having a head engaging the end face oi.' the collar, said parts being so constructed and related that when the shank is pulled through the member in a direction to urge the head against the collar, the reduced portion of the member and a portion thereof adjacent thereto bulb outwardly in sequential order.

29. In combination, a tubular female member adapted to extend through structural openings and having portions adapted to project beyond both sides of the structure, a male rivet member extending through the female member and having a head on one end engaging one end of vthe female member, and a shank portion projecting beyond the other end of the female member, and means for eilecting the formation of a plurality of adjacent heads on the female member between the structure and the male member head, when the projecting shank portion of the male member is pulled away from the end of the female member adjacent thereto, and the reactionary force or a substantially equal force is applied to 5 such end of the female member.

30. A rivet comprising a tubular member in which integral adjacent portions thereof have different resistances to outward expansion, and means including a member extending through l0 said tubular member and having a head portion for axially compressing said tubular member to expand said portions sequentially in the order of their differing resistances.

31. A rivet comprising a tubular means having 15 a portion adaptedgto project through a structure to be riveted, a second portion adapted to project beyond one side of the structure' and to be expanded by axial forces into a head and a third portion outwardly of the second portion and ex- 20 pansible by axial forces into a reinforcing head, a pin extending through the tubular means, and means on the end of the pin for applying axial forces to said second and third portions so as to expand them when the rivet is set. 25

32. A rivet comprising a pin adapted to project through a structure to be riveted and having a portion adapted to extend beyond said structure, means surrounding the pin adjacent the portion extending beyond said structure and expansible by axial `forces, and meanssurrounding the pin outwardly of the first meansand expansible by axial forces for reinforcing the first means when axial forces are applied. 35

LOUIS C. HUCK. 

